Preheat oven to 375F. In a large bowl, mix together flours, cocoa powder, sugar, baking powder, baking soda and salt.
Add in vanilla extract, apple cider vinegar, almond milk and vegetable oil. Whisk until smooth.
Spray a donut pan with nonstick cooking spray (make sure it does not have flour in it if you need to be gluten-free).
Spoon or pipe batter into the donut pan. The batter should just about reach the top of the pan.
Bake at 375F for 10-14 minutes or until the donuts spring back when you touch them. Cool on a wire rack.
To make the frosting, add powdered sugar and cocoa powder to a medium sized bowl. Whisk to combine.
Add almond milk one tablespoon at a time until your preferred consistency is reached. You don't want it to be so thin that it drips right off the donut, but too thick and you won't be able to dip the donuts successfully without them crumbling.
When the donuts are cooled, dip them into the frosting and shake off any excess. Place back on wire rack and sprinkle with rainbow sprinkles if desired.